See render progress in VSE
That just depends on what you set your Display to in your Render Properties:



Set it to Image Editor, Full Screen or New Window to see the result as it's being rendered.

Though you have to keep in mind that Frames that originate from a Movie Clip, Video Strip or Image Strip won't be rendered partially but as a whole image anyways. So you will only see real rendered images that originate from a 3D scene.